With development of wireless communications technologies, various wireless application requirements increase rapidly, and spectrum resources attracts ever-increasing attention. A static spectrum allocation strategy used in a current stage causes low spectrum resource utilization.
Recently, a secondary use method of a “licensed frequency band” draws extensive attention, and is an effective way to implement dynamic spectrum access (DSA for short). The dynamic spectrum access means that a secondary user terminal detects an available spectrum hole by spectrum sensing, and accesses a spectrum in a manner of opportunistic access. The secondary user terminal refers to an unlicensed user terminal.
When accessing a network, the secondary user terminal usually uses a preset subcarrier mode. In this way, the user terminal enables all or most of antenna channels according to the preset subcarrier mode, and accesses the network by using enabled antenna channels. However, in this case, the enabled antenna channels are far more than a service requirement, thereby easily causing a waste of the spectrum resources.